Organogenesis relies on the SoxC transcription factors for the survival of neural and mesenchymal progenitors

During organogenesis, neural and mesenchymal progenitor cells give rise to many cell lineages, but their molecular requirements for self-renewal and lineage decisions are incompletely understood. Here we show that their survival critically relies on the redundantly acting SoxC transcription factors Sox4, Sox11 and Sox12. The more SoxC alleles are deleted in mouse embryos, the more severe and widespread organ hypoplasia is. SoxC triple-null embryos die at mid-gestation unturned and tiny, with normal patterning and lineage specification, but with massively dying neural and mesenchymal progenitor cells. Specific inactivation of SoxC genes in neural and mesenchymal cells leads to selective apoptosis of these cells, suggesting SoxC cell-autonomous roles. Tead2 functionally interacts with the SoxC genes in embryonic development, and is a direct target of the SoxC proteins. The SoxC genes therefore ensure neural and mesenchymal progenitor cell survival and act in part by activating this transcriptional mediator of the Hippo signaling pathway. During organogenesis, neural and mesenchymal progenitor cells give rise to many cell lineages, but their molecular requirements for self-renewal and lineage decisions are incompletely understood. Here we show that their survival critically relies on the redundantly acting SoxC transcription factors Sox4, Sox11 and Sox12. The more SoxC alleles are deleted in mouse embryos, the more severe and widespread organ hypoplasia is. SoxC triple-null embryos die at mid-gestation unturned and tiny, with normal patterning and lineage specification, but with massively dying neural and mesenchymal progenitor cells. Specific inactivation of SoxC genes in neural and mesenchymal cells leads to selective apoptosis of these cells, suggesting SoxC cell-autonomous roles. Tead2 functionally interacts with the SoxC genes in embryonic development, and is a direct target of the SoxC proteins. The SoxC genes therefore ensure neural and mesenchymal progenitor cell survival and act in part by activating this transcriptional mediator of the Hippo signaling pathway. Total RNA isolated from limb bud cells in culture treated with Cre recombinase expressing adenovirus to inactivate floxed SoxC genes was compared to total RNA isolated from cells treated with LacZ expressing adenovirus as well as untreated cells as controls.